Mattia Pistone is a PhD student at the Institute for Geochemistry and Petrology at ETH Zurich (Switzerland). In my PhD project (SNF; grant 200020-120221) I have experimentally investigated the rheology of three-phase magmas (composed of crystals, gas bubbles and silicate melt in different relative proportions) under simple shear deformation at high temperature and high pressure conditions at Rock Deformation Laboratory at ETH Zurich. In my poster I present new experimental results showing two Non-Newtonian behaviors: shear thinning (decrease of viscosity with increasing strain rate) at high crystallinity; shear thickening (increase of viscosity with increasing strain rate) at low crystallinity. Shear thinning is associated with crystal size reduction and shear banding. Shear thickening is the expression of bubble coalescence and outgassing. The microstructural and rheological results have been combined to constrain the flow mechanics of three-phase magmas. This work is also published in Journal of
Geophysical Research (doi:10.1029/2011JB008986).

About EGU

EGU, the European Geosciences Union, is Europe’s premier geosciences union, dedicated to the pursuit of excellence in the Earth, planetary, and space sciences for the benefit of humanity, worldwide. It was established in September 2002 as a merger of the European Geophysical Society (EGS) and the European Union of Geosciences (EUG), and has headquarters in Munich, Germany.